DIETFITS Study (Diet Intervention Examining the Factors Interacting With Treatment Success

NCT01826591 | Completed

• 4 other identifiers: 223051R01DK091831T32HL007034UL1TR001085
• Study Type: interventional
• Target: 609
• Locations: 1 country
• Sites: 1

Brief Summary

Genomics research is advancing rapidly, and links between genes and obesity continue to be discovered and better defined. A growing number of single nucleotide polymorphisms (SNPs) in multiple genes have been shown to alter an individual's response to dietary macronutrient composition. Based on prior genetic studies evaluating the body's physiological responses to dietary carbohydrates or fats, the investigators identified multi-locus genotype patterns with SNPs from three genes (FABP2, PPARG, and ADRB2): a low carbohydrate-responsive genotype (LCG) and a low fat-responsive genotype (LFG). In a preliminary, retrospective study (using the A TO Z weight loss study data), the investigators observed a 3-fold difference in 12-month weight loss for initially overweight women who were determined to have been appropriately matched vs. mismatched to a low carbohydrate (Low Carb) or low fat (Low Fat) diet based on their multi-locus genotype pattern. The primary objective of this study is to confirm and expand on the preliminary results and determine if weight loss success can be increased if the dietary approach (Low Carb vs. Low Fat) is appropriately matched to an individual' s genetic predisposition (Low Carb Genotype vs. Low Fat Genotype) toward those diets.

Conditions

Obesity; Insulin Resistance

Outcome Measures

Primary Outcomes (1)

• Change from baseline in weight at 12 months

  Weight change was calculated as the 12 month value minus the baseline value. The study was designed to determine if either insulin secretion or genotype pattern (low-fat genotype pattern vs .low-carb genotype pattern) were significant effect modifiers of 12-month weight loss for the two diet arms (e.g., 2X2 analyses).

  Baseline and 12 months

Secondary Outcomes (10)

• Change from baseline in LDL cholesterol at 12 months

  Baseline and 12 months

• Change from baseline in HDL cholesterol at 12 months

  Baseline and 12 months

• Change from baseline in triglycerides at 12 months

  Baseline and 12 months

• Change from baseline in fasting insulin at 12 months

  Baseline and 12 months

• Change from baseline in fasting glucose at 12 months

  Baseline and 12 months

Study Arms (2)

Experimental: Low-Carbohydrate Diet

EXPERIMENTAL

Healthy, Low-Carbohydrate Diet

Behavioral: Low-Carbohydrate Diet; Behavioral: Mobile App

Experimental: Low-Fat Diet

EXPERIMENTAL

Healthy, Low-Fat Diet

Behavioral: Low-Fat Diet; Behavioral: Mobile App

Interventions

Low-Carbohydrate Diet BEHAVIORAL

Counseling/instruction on how to follow a low-carbohydrate diet.

Experimental: Low-Carbohydrate Diet

Low-Fat Diet BEHAVIORAL

Counseling/instruction on how to follow a low-fat diet.

Experimental: Low-Fat Diet

Mobile App BEHAVIORAL

Mobile app to increase vegetable consumption. Participants with iPhones will be re-randomized to receive a mobile app beginning at either months 4-5 or months 7-8. The first phase during months 4-7 will be used to compare the effect of a mobile app (intervention) vs. no mobile app (waiting-list control). The a priori hypothesis is that vegetable consumption will increase among those who receive the app in both diet groups.

Experimental: Low-Carbohydrate Diet; Experimental: Low-Fat Diet

Eligibility Criteria

• Age: 18 Years - 50 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• Age: \> 18 years of age
• Women: Pre-menopausal (self-report) and \<50 years of age
• Men: \<50 years of age
• BMI (body mass index): 27-40 kg/m2 (need to lose \>10% body weight to achieve healthy BMI)
• Body weight stable for the last two months, and not actively on a weight loss plan
• No plans to move from the area over the next two years
• Available and able to participate in the evaluations and intervention for the study period
• Willing to accept random assignment
• participate if they have been stable on such medications for at least three months
• Ability and willingness to give written informed
• No known active psychiatric illness

You may not qualify if:

• Subjects with the following conditions will be excluded (determined by self-report):
• Pregnant, lactating, within 6 months post-partum, or planning to become pregnant in the next 2 years
• Diabetes (type 1 and 2) or history of gestational diabetes or on hypoglycemic medications for any other indication
• Prevalent diseases: Malabsorption, renal or liver disease, active neoplasms, recent myocardial infarction (\<6 months)(patient self-report and, if available, review of labs from primary care provider)
• Smokers (because of effect on weight and lipids)
• History of serious arrhythmias, or cerebrovascular disease
• Uncontrolled hyper- or hypothyroidism (TSH not within normal limits)
• Medications: Lipid lowering, antihypertensive medications, and those known to affect weight/energy expenditure
• Excessive alcohol intake (self-reported, \>3 drinks/day)
• Musculoskeletal disorders precluding regular physical activity
• Unable to follow either of the two study diets for reasons of food allergies or other (e.g., vegan)
• Currently under psychiatric care, or taking psychiatric medications
• Inability to communicate effectively with study personnel

Sponsors & Collaborators

• Stanford University: lead
• Nutrition Science Initiative: collaborator
• National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK): collaborator
• National Heart, Lung, and Blood Institute (NHLBI): collaborator
• National Center for Advancing Translational Sciences (NCATS): collaborator

Study Sites (1)

Stanford University School of Medicine

Stanford, California, 94305, United States

Location

Related Publications (19)

• Mummah SA, Robinson TN, King AC, Gardner CD, Sutton S. IDEAS (Integrate, Design, Assess, and Share): A Framework and Toolkit of Strategies for the Development of More Effective Digital Interventions to Change Health Behavior. J Med Internet Res. 2016 Dec 16;18(12):e317. doi: 10.2196/jmir.5927.

  PMID: 27986647 BACKGROUND

• Mummah SA, Mathur M, King AC, Gardner CD, Sutton S. Mobile Technology for Vegetable Consumption: A Randomized Controlled Pilot Study in Overweight Adults. JMIR Mhealth Uhealth. 2016 May 18;4(2):e51. doi: 10.2196/mhealth.5146.

  PMID: 27193036 BACKGROUND

• Mummah SA, King AC, Gardner CD, Sutton S. Iterative development of Vegethon: a theory-based mobile app intervention to increase vegetable consumption. Int J Behav Nutr Phys Act. 2016 Aug 8;13:90. doi: 10.1186/s12966-016-0400-z.

  PMID: 27501724 BACKGROUND

• Stanton MV, Robinson JL, Kirkpatrick SM, Farzinkhou S, Avery EC, Rigdon J, Offringa LC, Trepanowski JF, Hauser ME, Hartle JC, Cherin RJ, King AC, Ioannidis JP, Desai M, Gardner CD. DIETFITS study (diet intervention examining the factors interacting with treatment success) - Study design and methods. Contemp Clin Trials. 2017 Feb;53:151-161. doi: 10.1016/j.cct.2016.12.021. Epub 2016 Dec 24.

  PMID: 28027950 BACKGROUND

• Gardner CD, Trepanowski JF, Del Gobbo LC, Hauser ME, Rigdon J, Ioannidis JPA, Desai M, King AC. Effect of Low-Fat vs Low-Carbohydrate Diet on 12-Month Weight Loss in Overweight Adults and the Association With Genotype Pattern or Insulin Secretion: The DIETFITS Randomized Clinical Trial. JAMA. 2018 Feb 20;319(7):667-679. doi: 10.1001/jama.2018.0245.

  PMID: 29466592 BACKGROUND

• Shih CW, Hauser ME, Aronica L, Rigdon J, Gardner CD. Changes in blood lipid concentrations associated with changes in intake of dietary saturated fat in the context of a healthy low-carbohydrate weight-loss diet: a secondary analysis of the Diet Intervention Examining The Factors Interacting with Treatment Success (DIETFITS) trial. Am J Clin Nutr. 2019 Feb 1;109(2):433-441. doi: 10.1093/ajcn/nqy305.

  PMID: 30649213 BACKGROUND

• Fielding-Singh P, Patel ML, King AC, Gardner CD. Baseline Psychosocial and Demographic Factors Associated with Study Attrition and 12-Month Weight Gain in the DIETFITS Trial. Obesity (Silver Spring). 2019 Dec;27(12):1997-2004. doi: 10.1002/oby.22650. Epub 2019 Oct 21.

  PMID: 31633313 BACKGROUND

• Grembi JA, Nguyen LH, Haggerty TD, Gardner CD, Holmes SP, Parsonnet J. Gut microbiota plasticity is correlated with sustained weight loss on a low-carb or low-fat dietary intervention. Sci Rep. 2020 Jan 29;10(1):1405. doi: 10.1038/s41598-020-58000-y.

  PMID: 31996717 BACKGROUND

• Figarska SM, Rigdon J, Ganna A, Elmstahl S, Lind L, Gardner CD, Ingelsson E. Proteomic profiles before and during weight loss: Results from randomized trial of dietary intervention. Sci Rep. 2020 May 13;10(1):7913. doi: 10.1038/s41598-020-64636-7.

  PMID: 32404980 BACKGROUND

• Lai CQ, Parnell LD, Das SK, Gardner CD, Ordovas JM. Differential weight-loss responses of APOA2 genotype carriers to low-carbohydrate and low-fat diets: the DIETFITS trial. Obesity (Silver Spring). 2025 Jun;33(6):1048-1057. doi: 10.1002/oby.24288. Epub 2025 May 1.

  PMID: 40310284 DERIVED

• Krauss RM, Fisher LM, King SM, Gardner CD. Changes in soluble LDL receptor and lipoprotein fractions in response to diet in the DIETFITS weight loss study. J Lipid Res. 2024 Mar;65(3):100503. doi: 10.1016/j.jlr.2024.100503. Epub 2024 Jan 19.

  PMID: 38246235 DERIVED

• Hauser ME, Hartle JC, Landry MJ, Fielding-Singh P, Shih CW, Qin F, Rigdon J, Gardner CD. Association of dietary adherence and dietary quality with weight loss success among those following low-carbohydrate and low-fat diets: a secondary analysis of the DIETFITS randomized clinical trial. Am J Clin Nutr. 2024 Jan;119(1):174-184. doi: 10.1016/j.ajcnut.2023.10.028. Epub 2023 Nov 4.

  PMID: 37931749 DERIVED

• Soto-Mota A, Pereira MA, Ebbeling CB, Aronica L, Ludwig DS. Evidence for the carbohydrate-insulin model in a reanalysis of the Diet Intervention Examining The Factors Interacting with Treatment Success (DIETFITS) trial. Am J Clin Nutr. 2023 Mar;117(3):599-606. doi: 10.1016/j.ajcnut.2022.12.014. Epub 2023 Jan 6.

  PMID: 36811468 DERIVED

• Hartle JC, Zawadzki RS, Rigdon J, Lam J, Gardner CD. Development and evaluation of a novel dietary bisphenol A (BPA) exposure risk tool. BMC Nutr. 2022 Dec 6;8(1):143. doi: 10.1186/s40795-022-00634-4.

  PMID: 36474269 DERIVED

• Cauwenberghs N, Prunicki M, Sabovcik F, Perelman D, Contrepois K, Li X, Snyder MP, Nadeau KC, Kuznetsova T, Haddad F, Gardner CD. Temporal changes in soluble angiotensin-converting enzyme 2 associated with metabolic health, body composition, and proteome dynamics during a weight loss diet intervention: a randomized trial with implications for the COVID-19 pandemic. Am J Clin Nutr. 2021 Nov 8;114(5):1655-1665. doi: 10.1093/ajcn/nqab243.

  PMID: 34375388 DERIVED

• Fragiadakis GK, Wastyk HC, Robinson JL, Sonnenburg ED, Sonnenburg JL, Gardner CD. Long-term dietary intervention reveals resilience of the gut microbiota despite changes in diet and weight. Am J Clin Nutr. 2020 Jun 1;111(6):1127-1136. doi: 10.1093/ajcn/nqaa046.

  PMID: 32186326 DERIVED

• Oppezzo MA, Stanton MV, Garcia A, Rigdon J, Berman JR, Gardner CD. To Text or Not to Text: Electronic Message Intervention to Improve Treatment Adherence Versus Matched Historical Controls. JMIR Mhealth Uhealth. 2019 Apr 9;7(4):e11720. doi: 10.2196/11720.

  PMID: 30964436 DERIVED

• Guo J, Robinson JL, Gardner CD, Hall KD. Objective versus Self-Reported Energy Intake Changes During Low-Carbohydrate and Low-Fat Diets. Obesity (Silver Spring). 2019 Mar;27(3):420-426. doi: 10.1002/oby.22389. Epub 2019 Jan 22.

  PMID: 30672127 DERIVED

• Mummah S, Robinson TN, Mathur M, Farzinkhou S, Sutton S, Gardner CD. Effect of a mobile app intervention on vegetable consumption in overweight adults: a randomized controlled trial. Int J Behav Nutr Phys Act. 2017 Sep 15;14(1):125. doi: 10.1186/s12966-017-0563-2.

  PMID: 28915825 DERIVED

Related Links

• Study description and results summary

MeSH Terms

Conditions

Obesity; Insulin Resistance

Interventions

Diet, Carbohydrate-Restricted; Diet, Fat-Restricted

Condition Hierarchy (Ancestors)

Overweight; Overnutrition; Nutrition Disorders; Nutritional and Metabolic Diseases; Body Weight; Signs and Symptoms; Pathological Conditions, Signs and Symptoms; Hyperinsulinism; Glucose Metabolism Disorders; Metabolic Diseases

Intervention Hierarchy (Ancestors)

Diet Therapy; Nutrition Therapy; Therapeutics; Diet; Nutritional Physiological Phenomena; Diet, Food, and Nutrition; Physiological Phenomena

Study Officials

• Christopher D Gardner, PhD

  Stanford University

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: DOUBLE
• Who Masked: INVESTIGATOR, OUTCOMES ASSESSOR
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Professor of Medicine

Study Record Dates

• First Submitted: March 27, 2013
• First Posted: April 8, 2013
• Study Start: January 1, 2013
• Primary Completion: May 1, 2016
• Study Completion: May 1, 2016
• Last Updated: February 21, 2023

Record last verified: 2023-02

Data Sharing

• IPD Sharing: Will not share

Locations

US (1)